The number of rigs drilling for oil in the U.S. increased by 26 this week to 791, Baker Hughes, a GE company, reported.

The latest U.S. oil-rig count showed the highest weekly number in 34 months. The last time the oil-rig count stood above 791 was April 2, 2015, when it reached 802 and has continued to remain below that mark.

The U.S. oil-rig count is typically viewed as a proxy for activity in the sector. After peaking at 1,609 in October 2014, low oil prices put downward pressure on production and the rig count fell sharply. The oil-rig count had generally been rising since June 2016 before reaching a plateau in August 2017.

The nation's gas-rig count was up by 3 to 184 in the past week, according to oil-field services company Baker Hughes.

The U.S. offshore-rig count was unchanged from last week at 16, which is 5 less than a year ago.

U.S. crude futures recently fell 3.7% to $58.88 a barrel on the New York Mercantile Exchange in afternoon trading Friday. Brent crude, the global benchmark, dropped 3.5%, to $62.51 a barrel, on ICE Futures Europe.

Write to Aisha Al-Muslim at aisha.al-muslim@wsj.com

Corrections & Amplifications

This item was corrected at 2:42 p.m. ET to show that the latest U.S. oil-rig count showed the highest weekly number in 34 months, not 22 months.